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//convert.c by Steve Rhoads 4/26/01

//Now uses the ELF format (get gccmips_elf.zip)

//set $gp and zero .sbss and .bss

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#define BUF_SIZE (1024*1024) 

/*Assumes running on PC little endian*/

#define ntohl(A) (((A)>>24)|(((A)&0x00ff0000)>>8)|(((A)&0xff00)<<8)|((A)<<24))

#define ntohs(A) ((((A)&0xff00)>>8)|((A)<<8))

#define EI_NIDENT 16

#define SHT_PROGBITS 1

#define SHT_STRTAB 3

#define SHT_NOBITS 8

typedef struct

{

   unsigned char  e_ident[EI_NIDENT];

   unsigned short e_e_type;

   unsigned short e_machine;

   unsigned long  e_version;

   unsigned long  e_entry;

   unsigned long  e_phoff;

   unsigned long  e_shoff;

   unsigned long  e_flags;

   unsigned short e_ehsize;

   unsigned short e_phentsize;

   unsigned short e_phnum;

   unsigned short e_shentsize;

   unsigned short e_shnum;

   unsigned short e_shstrndx;

}

ElfHeader;

typedef struct

{

   unsigned long p_type;

   unsigned long p_offset;

   unsigned long p_vaddr;

   unsigned long p_paddr;

   unsigned long p_filesz;

   unsigned long p_memsz;

   unsigned long p_flags;

   unsigned long p_align;

}

Elf32_Phdr;

typedef struct

{

   unsigned long sh_name;

   unsigned long sh_type;

   unsigned long sh_flags;

   unsigned long sh_addr;

   unsigned long sh_offset;

   unsigned long sh_size;

   unsigned long sh_link;

   unsigned long sh_info;

   unsigned long sh_addralign;

   unsigned long sh_entsize;

}

Elf32_Shdr;

void set_low(char *ptr, unsigned long address, unsigned long value)

{

   unsigned long opcode;

   opcode = *(unsigned long *)(ptr + address);

   opcode = ntohl(opcode);

   opcode = (opcode & 0xffff0000) | (value & 0xffff);

   opcode = ntohl(opcode);

   *(unsigned long *)(ptr + address) = opcode;

}

int main(int argc, char *argv[])

{

   FILE *infile, *outfile, *txtfile;

   unsigned char *buf, *code;

   long size, stack_pointer;

   unsigned long length, d, i, gp_ptr = 0;

   unsigned long bss_start = 0, bss_end = 0;

   ElfHeader *elfHeader;

   Elf32_Phdr *elfProgram;

   Elf32_Shdr *elfSection;

   printf("test.exe -> code.txt & test2.exe\n");

   infile = fopen("test.exe", "rb");

   if(infile == NULL)

   {

      printf("Can't open test.exe");

      return 0;

   }

   buf = (unsigned char *)malloc(BUF_SIZE);

   size = (int)fread(buf, 1, BUF_SIZE, infile);

   fclose(infile);

   code = (unsigned char *)malloc(BUF_SIZE);

   memset(code, 0, BUF_SIZE);

   elfHeader = (ElfHeader *)buf;

   if(strncmp(elfHeader->e_ident + 1, "ELF", 3))

   {

      printf("Error:  Not an ELF file!\n");

      printf("Use the gccmips_elf.zip from opencores/projects/plasma!\n");

      return -1;

   }

   elfHeader->e_entry = ntohl(elfHeader->e_entry);

   elfHeader->e_phoff = ntohl(elfHeader->e_phoff);

   elfHeader->e_shoff = ntohl(elfHeader->e_shoff);

   elfHeader->e_flags = ntohl(elfHeader->e_flags);

   elfHeader->e_phentsize = ntohs(elfHeader->e_phentsize);

   elfHeader->e_phnum = ntohs(elfHeader->e_phnum);

   elfHeader->e_shentsize = ntohs(elfHeader->e_shentsize);

   elfHeader->e_shnum = ntohs(elfHeader->e_shnum);

   length = 0;

   for(i = 0; i < elfHeader->e_phnum; ++i)

   {

      elfProgram = (Elf32_Phdr *)(buf + elfHeader->e_phoff +

                         elfHeader->e_phentsize * i);

      elfProgram->p_type = ntohl(elfProgram->p_type);

      elfProgram->p_offset = ntohl(elfProgram->p_offset);

      elfProgram->p_vaddr = ntohl(elfProgram->p_vaddr);

      elfProgram->p_filesz = ntohl(elfProgram->p_filesz);

      elfProgram->p_memsz = ntohl(elfProgram->p_memsz);

      elfProgram->p_flags = ntohl(elfProgram->p_flags);

      if(elfProgram->p_vaddr < BUF_SIZE)

      {

         //printf("[0x%x,0x%x,0x%x]\n", elfProgram->p_vaddr,

         //   elfProgram->p_offset, elfProgram->p_filesz);

         memcpy(code + elfProgram->p_vaddr, buf + elfProgram->p_offset,

                 elfProgram->p_filesz);

         length = elfProgram->p_vaddr + elfProgram->p_memsz;

      }

   }

   for(i = 0; i < elfHeader->e_shnum; ++i)

   {

      elfSection = (Elf32_Shdr *)(buf + elfHeader->e_shoff +

                         elfHeader->e_shentsize * i);

      elfSection->sh_name = ntohl(elfSection->sh_name);

      elfSection->sh_type = ntohl(elfSection->sh_type);

      elfSection->sh_addr = ntohl(elfSection->sh_addr);

      elfSection->sh_offset = ntohl(elfSection->sh_offset);

      elfSection->sh_size = ntohl(elfSection->sh_size);

      if(elfSection->sh_type == SHT_PROGBITS)

      {

         if(elfSection->sh_addr > gp_ptr)

            gp_ptr = elfSection->sh_addr;

      }

      if(elfSection->sh_type == SHT_NOBITS)

      {

         if(bss_start == 0)

         {

            bss_start = elfSection->sh_addr;

         }

         bss_end = elfSection->sh_addr + elfSection->sh_size;

      }

   }

   if(bss_start == length)

   {

      bss_start = length;

      bss_end = length + 4;

   }

   /*Initialize the $gp register for sdata and sbss */

   gp_ptr += 0x7ff0;

   printf("gp_ptr=0x%x ", gp_ptr);

   /*modify the first opcodes in boot.asm */

   /*modify the lui opcode */

   set_low(code, 0, gp_ptr >> 16);

   /*modify the ori opcode */

   set_low(code, 4, gp_ptr & 0xffff);

   /*Clear .sbss and .bss */

   printf(".sbss=0x%x .bss_end=0x%x ", bss_start, bss_end);

   set_low(code, 8, bss_start >> 16);

   set_low(code, 12, bss_start & 0xffff);

   set_low(code, 16, bss_end >> 16);

   set_low(code, 20, bss_end & 0xffff);

   /*Set stack pointer */

   stack_pointer = bss_end + 512;

   printf("Stack_pointer=0x%x\n", stack_pointer);

   set_low(code, 24, stack_pointer >> 16);

   set_low(code, 28, stack_pointer & 0xffff);

   /*write out code.txt */

   outfile = fopen("test2.exe", "wb");

   fwrite(code, length, 1, outfile);

   fclose(outfile);

   txtfile = fopen("code.txt", "w");

   for(i = 0; i <= length; i += 4)

   {

      d = ntohl(*(unsigned long *)(code + i));

      fprintf(txtfile, "%8.8x\n", d);

   }

   fclose(txtfile);

   free(buf);

   return 0;

}